1. Field of the Invention
The invention relates to the technical field of electronic ballast for a fluorescent lamp, in particular to a single-stage electronic ballast for a fluorescent lamp.
2. Background of the Invention
The design of a conventional electronic ballast for a fluorescent lamp makes use of a set of electronic ballast to drive a single fluorescent lamp tube. However, when there is a need to drive a plurality of fluorescent lamp tubes, the design of using a set of electronic ballast to drive a single fluorescent lamp tube will result in much complicated circuit architecture and too large volume. Therefore, the existing electronic ballast technique for the fluorescent lamp is developed with the tendency of using a set of the electronic ballast to drive a plurality of fluorescent lamp tubes. FIG. 1 shows a circuit structure of a conventional two-stage electronic ballast for a fluorescent lamp, in which at a first stage, a boost-typed converter 101 serves as a power factor correction circuit, and at a latter stage, a class D resonant inverter 103 is used for driving a fluorescent lamp tube. Such a circuit structure of the electronic ballast for a fluorescent lamp is mainly adopted at present.
However, it can be found from FIG. 1 that for a two-stage electronic ballast, two sets of control circuits are required to respectively drive the converter 101 and the inverter 103, and three switch elements are needed, causing complicated circuit, big switching loss and low efficiency.
Hence, there are several defects in the conventional electronic ballasts for the fluorescent lamp which need overcome.